Seconds after telling anyone you're a Lonely Planet author, they'll ask how you got the job. Sometimes it's just polite curiousity other times it's because they think it sounds like a dream job, but mostly it's because they believe there's an arcane ritual that you have to pass through be annointed by guidebook brahmins. If there was a ritual then I missed it and the truth is it requires an odd collection of skills.
If you're looking to get a job as a guidebook author the first place to check is the Lonely Planet's own instructions on becoming an author. For the last year there's been a hiring freeze, but word is that this will soon be thawing as they begin refreshing the pool of around 300 authors.
There's no secret to the recruitment process. As well as normal material like a CV and examples of previous work, new authors can be asked to write a sample chapter to show how you'd write a guidebook. You'll get some instructions on how to write this so follow these as closely as you can.
Choosing where to write your sample chapter about is crucial. It needs to both showcase your writing but also be the kind of place you'd see in a guidebook. Originally I did mine on a small town and found there just wasn't enough material. Plus there wasn't much significance or history to the town so it was hard to see why it would appear in guidebook with 2000 words dedicated to it. It's about selecting somewhere that suits the word count. Trying to cover all of metropolitan Melbourne is tough and will give you only the roughest sketch, but covering a suburb in depth is going to give richer writing.
And what about your writing? Travel writing is really competitive so your sample needs to be distinctive and show that you've got your own style. Brochurese ('stunning vistas' or 'luxury options' anyone?) and cliches are the unexceptional kids picked around the middle in playground football. Challenge yourself to write like nobody else in the slush pile and even if you're bad at least you'll be exceptionally bad.
Accuracy is always important and you can bet that anyone assessing it will fact check with a phonecall or even visit. In guidebooks even the best writing is worthless if your basic information is wrong and you see a lot of reader's letters where people have got the maps wrong.
Oh yeah - the maps. You need to do a sample map that points out everything you mention in the text. Map-text consistency is important, but maps need to be both clear and complete. It's not just about writing and you'll need to be an amateur cartographer as well. Generally you can work from existing maps but knowing where to put each item is important.
Having in-depth knowledge of destinations is important and having a language or two is useful. The Lonely Planet website sometimes targets difficult destinations where they need specific skills or specialists. Getting the balance between writing skills and specialist knowledge is important though so lecturing professors need not apply (though these kind of specialists might be useful on a specific books).
Many Lonely Planet authors (including me) get experience with house style and guidebooks by working in-house. This used to be called 'jumping the fence' as even in-house staff have to do the same process of writing a sample chapter and have it assessed.
Assessment is usually done by skilled editors who've worked on their fair share of books. They're looking for something that has no errors (so don't just spell check your work) but also reads well and is accurate. Getting rejected can give you some good feedback that will improve your writing and your chances next time.
While not quite an arcane ritual, the sample is a big hurdle but if you're given the nod as an author then you can start pitching for books anywhere in the world.